The “Everybody shufflin’” achievment is not tracking when drawing “Acorn” from “Vibrant squirrel” (which is a spell that casts when drawn).
What game mode were you playing?
Standard, wild, casual, arena, tavern brawl, solo adventure, ???
Just tried with Vibrant Squirrel, Asteroids (Moonstone Mauler), Portal Keeper and Ysera Unleashed, and it seems Asteroids are working. The rest was not.